2600, Attacking Enterprise Networks

Since 1984 the magazine “2600” has been the undisputed publication created by and for hackers and phone phreakers worldwide. The January 2017 cover to the right is misleading, the magazine isn’t named after the Atari system, but rather the 2600 Hz tone ATT used, that phreakers leveraged, to control long distance phone lines. Most article bylines are hacker handles, rather than proper names, as the articles themselves don’t always paint inside the numbers. In January 2017 a hacker with the handle “Daelphinux” published the first of a five-part series of articles titled “Successful Network Attacks – Phase One” and every quarter since then he’s published the next phase, with the final Phase Five hitting the streets today January 2, 2018. This collection of five articles is perhaps the most concise executive-level summary of how an attacker breaches an enterprise that I’ve read thus far. Hopefully, I won’t offend Daelphinux by attempting to summarizing the key points of his five articles in this single blog post. I strongly suggest that everyone reading this review the original text in these five issues of 2600.

Daelphinux classified a Successful Network Attack into five phases:

Reconnaissance – “Gathering as much useful information about the targets as possible.”

Scanning – “Gathering useful information about the target’s networks and any possible exploits.”

Gaining Access – “Getting into the network to be able to accomplish the attack’s goal.”

Maintaining Access – “Ensuring access to the network persists long enough to accomplish the attack’s goal.”

Covering Tracks – “Obfuscating the attacker’s presence on the network such that they cannot be traced.”

Each phase builds on the first, with Daelphinux envisioning this as a pyramid with phase one on the bottom, and each successive phase building on the prior one. Attackers will need tools and skills at each level in order to conduct a successful attack. Defenders, the enterprise admins, will also need tools and skills for several phases to detect and defend against an attack.

Phase 1 – Reconnaissance. As defined by Daelphinux the attacker seeks to gather all the raw data they can on their target before actively engaging them. The key here is in gathering only the “useful” data, as an attacker will rapidly accumulate an enormous pile of information. This information should come from a wide variety of sources including, but not limited to: deep web searches, web crawling those results, calling all the targets publicly available phone numbers to learn everything they can about the target, draining “whois” databases for all known corporate DNS assets, launching phishing and email scams at targeted employes and generic email address, real-life social engineering by making new friends, and finally dumpster diving.

All these efforts will produce a heap of information, but most of it will be useless. Here is where intelligent sifting comes in. Important information is often in handwritten notes, or cast of printouts such as printer test configuration pages, IP table listings, usernames, equipment manufacturer shipping boxes, operating system manuals, internal organizational charts & structures, and corporate policies (especially password).

Recognizing these reconnaissance efforts is the initial step toward thwarting an attack. For example, reviewing security footage looking for dumpster divers might sound trivial, but differentiating between an attacker and someone looking something to sell for their next meal can be challenging. Other activities like social engineering become far more complex to detect via video surveillance as these activities appear as background noise. While this phase might be the toughest to detect, it is the easiest to defend against. If you can cut off the flow of information outside enterprise you can seriously hamper their reconnaissance efforts. To do this you can hide the whois records, destroy printed copies of purchase orders, destroy shipping boxes used to pack new servers or appliances, destroy discarded manuals, remove and clean printer hard drives, make sure all in-house shredders use cross-cut shredding and finally burn any really sensitive info that has already been shredded. Much of this can be addressed through procedures and training.

Phase 2 – Scanning, In April Daelphinux covered the details of this phase. He said that when an attacker moves on to phase two they are committed, and unlikely to walk away. This phase is the first real step where the attacker can’t evade detection as they have to deploy active tools to electronically gather as much insight as they can. Tools like: Nmap, Nessus, Metasploit, ZAP, Xenotix or Grabber. Here they are looking to generate IP Maps, enumerate subnets, determine network speeds, the resilience of networks, open ports on clients, appliances & servers used, along with applications and the versions in production. All this scanning will provide the attacker with another huge heap of data to sift through with the eventual goal being to define the attack vectors that define the real “meat” of the attack.

This phase is the last chance for a defender to stop an attack before valuable assets are stolen. During this phase, administrators might notice network slowdowns, so on detecting these and investigating see if one IP address or a small range of addresses is touching a wide range of resources if so you are likely in the process of being scanned. Attackers will often launch the scanning phase remotely. So using network address translation (NAT) internally, next-generation firewalls, and current IPS & IDS appliances can in some cases detect this. It is always strongly recommended to be current in patching all your appliances and to follow proper admin process.

Phase 3 – Gaining Access, was published in 2600 in July of 2017. Without gaining access an attack isn’t an attack. Some of the key tools used are Metasploit and ZAP, but they will also leverage trojans, zombies, and backdoors to gain multiple toeholds into the enterprise’s network. Attackers often use remote shells instead of graphical tools, as shells often prove to be faster, more flexible and powerful.

Typically attackers operate from an endpoint that is not their intended target, for example leveraging another user’s machine to attack a server. By using another unsuspecting endpoint if it becomes compromised they can then move onto another workstation within the enterprise network. Attackers are typically interested in copying, moving, deleting and or altering files. In this article, we’re not interested in those seeking to launch a Denial of Service (DoS) attack, just those looking to exfiltrate value from the enterprise. Detecting attacks during this phase requires active monitoring, and the question is when, not if, you’ll detect an attacker. Doing active file audits, examining files that are changed outside of regularly expected intervals, watching for irregular traffic patterns, and reviewing access and error logs are all known methods of detecting an attack.

Phase 4 – Maintaining Access, was published in the October 2017 issue. This is the last phase where defending against an attack can successfully prevent data loss. Daelphinux stated that there are three things which should be kept in mind:

The Attacker has already breached the network.

The Attacker is actively attempting to achieve their goal.

Less experienced attackers tend to get overly comfortable with their success at this point.

This is the stage at which attackers are at their most vulnerable. They are moving around in plain sight within your network and can be detected if you’re looking for them. Network monitoring is the key to detection in this phase, but also, unfortunately, detection at this phase is also based on hope. You as the defender are hoping you discover them, and they are hoping their connection won’t get them detected and severed.

Skilled attackers will setup precautions to prevent this. One of the attacker’s strategies will be to take over network monitoring tools in an effort to circumvent detection. Enterprises need a heavy level of paranoia at this point to ensure that they are checking everything. Looking for the use of uncommon ports or protocols is another method for detecting attackers. Typically Intrusion Prevention (IPS) and Intrusion Detection Systems (IDS) and Security Information and Event Management Systems (SIEMS) are useful tools in ferreting out hackers. SIEMS themselves often are now targets for attackers. Multiple instances of these devices or appliances should be leveraged to thwart a takedown. Consider having these monitors watch each other, so in the event, one goes down you can use that as a potential indicator of an attack. If both or all monitors go down simultaneously then it’s very possible you’re under attack. Killing connections that meet certain criteria are vital to cutting off an attackers access, for example terminating connections that last longer than 25 minutes. Think that scene in the original “Transformers” when the general shouts “Cut the hard lines!”

Phase 5 – Covering Tracks, today January 2, 2018, we saw the latest issue of 2600 with Daelphinux final installment in the series on “Successful Network Attacks – Phase Five – Covering Tracks.” Once an attacker has reached phase five they’ve taken what they need, and now the coverup begins. Attempting to defend against this phase “is a form of damage control,” at best you’re preserving forensic evidence to hopefully reconstruct what they took after the fact. An attacker has to leave as cleanly as they entered otherwise they could dilute some of the value of what was taken. As Daelphinux points out, what good is a list of users and passwords if the passwords have all been changed. The same holds true of Malware and backdoors, you can’t sell a backdoor into an enterprise if it has been removed.

The best defense against this is redundant, and perhaps even hidden copies of logs. Attackers will often sanitize the logs they find, but they rarely go looking for additional copies of logs, especially if some effort has been made to hide and even secure them. It’s possible that if you have automated your logging such that multiple copies are generated, and accesses are tracked the attacker will notice this in phase three and just avoid it. Attackers will normally obfuscate both their IP and MAC addresses to further frustrate tracking them, often using addresses already on the network. Again, as mentioned in phase three setting connection limits, timeouts, and alerts when these are reached is often a good way to thwart or even detect an attacker. It should also be noted that attackers will often escalate their privilege on a system so they can disable logging. As Daelphinux noted disabling logging will often generate its own log event, but then after that, you won’t know what was done. Some attackers may even just erase or corrupt log files on the way out the door, a sort of “salt the earth” strategy to make determining what was taken that much more difficult. Regardless, a company will need to make some determinations on what was stolen or affected and alert their customers. A recent Ponemon report states that just cleaning up and dealing with a data breach in the US often costs companies $244/record.

Hats off to Daelphinux for authoring “Successful Network Attacks,” and “2600, The Hacker Quarterly” for publishing it.